In the fall of 2011, the CIA asked that Boston Marathon bombing suspect Tamerlan Tsarnaev 's name be added to a primary terrorism watch list after Russian officials raised concerns about his radical Islamist views and possible plans to travel abroad, The Washington Post reported Wednesday.

The CIA request was made to the National Counterterrorism Center, unidentified officials told the newspaper.

Tsarnaev's name was added to Terrorist Identities Datamart Environment database, but it was not clear which agency did do. The Post writes that the database "feeds a series of government watch lists, including the FBI's main Terrorist Screening Database and the Transportation Security Administration's 'no-fly' list."

The CIA's request came after the FBI had interviewed Tsarnaev and closed a preliminary investigation after Russian security authorities had also raised concerns.

The 26-year-old Tsarnaev died late Thursday after shootouts with police in Watertown, Mass.

His 19-year-old brother, Dzhokhar Tsarnaev, has been charged in connection with the deadly bombings that killed three people and injured more than 260 Monday. He is in a Boston hospital in fair condition with wounds suffered during the shootouts and manhunt.

Earlier Wednesday, their father said he and his wife would travel to the United States from Dagestan on Thursday to assist with the investigation.

FBI agents traveled to the Russian republic to interview Anzor Tsarnaev and his wife, Zubeidat Tsarnaev, to try to determine how their sons became radicalized.

She took a taxi to the offices of the Russian security services, or FSB, in Makhachkala, the capital of Dagestan, where she was interviewed by U.S. and Russian officials. But Tsarnaev was not questioned, telling officials he felt ill.

He later told the Russian news agency RIA Novosti that the couple would travel to the United States the next day to offer assistance.

A lawyer for the family said, however, that the family had not finalized their plans.

Investigators are looking into whether Tamerlan Tsarnaev, who spent six months in Russia's Caucasus in 2012, was influenced by the religious extremists who have waged an insurgency against Russian security services in the area for years. The brothers have roots in Dagestan and neighboring Chechnya, but neither spent much time in either place before the family moved to the United States a decade ago.

Shortly before he died, Tamerlan called his mother, TheWall Street Journal reported, telling her: "The police, they have started shooting at us; they are chasing us. Mama, I love you." Then the phone went dead.

Dzhokhar, who has answered some questions of U.S. investigators regarding the April 15 bombings at the finish line of the Boston Marathon, has said that he and his brother acted alone and without any help from anyone, foreign or domestic, according to a law enforcement official.

He has also said that the brothers were motivated by religious fervor and anger over U.S. involvement in the Iraq and Afghanistan wars.

The parents returned to Dagestan without their children several years ago. They have claimed that their sons are innocent of involvement in last week's bombings and are being framed by police.

She also gave an exclusive interview to Britain's Channel 4 News, calling the bombing a "a terrible thing."

"But I know that my kids have nothing to do with this," she said. "I know it. I am mother. I know my kids."

The U.S. Embassy delegation made the trip on Tuesday "because the investigation is ongoing, it's not over," said an embassy official, who spoke on condition of anonymity because he was not authorized to speak to the media. He said the U.S. team is working with the FSB.

"This is a horrible tragedy for our country, but one positive development might be closer cooperation on this set of issues with the Russian government," the embassy official said.

Anzor Tsarnaev is an ethnic Chechen born in Kyrgyzstan. Zubeidat Tsarnaev is an ethnic Avar from Dagestan.

It was unclear exactly which officials were carrying out the interviews, but the AFP news agency quoted an embassy official, who spoke on condition of anonymity, who said that the FBI is receiving cooperation from the Russian government in its investigation.

Heda Saratova, a prominent Chechen rights activist providing support to the distraught mother, said she first went in for questioning on Tuesday, returning late at night. Saratova said she had no details about the discussions, but that Zubeidat Tsarnaev said they were "cordial."

A Dagestan security source told AFP that the parents, asked about Tamerlan's trip to Dagestan in 2012, replied that he did not make contact with radical Islamists.

Abdurashid Magomedov, Dagestan's interior minister, has also denied that Tamerlan became a follower of radical Islam while in the republic, according to Russia's Interfax news agency.